Food tests · 食物检测
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| food tests/fuːd tests/ | 食物检测 | shí wù jiǎn cè |
| iodine/ˈaɪədiːn/ | 碘 | diǎn |
| reducing sugar/rɪˈdjuːsɪŋ ˈʃʊɡə/ | 还原糖 | huán yuán táng |
| Benedict's/ˈbenɪdɪkts/ | 本尼迪克特试剂 | běn ní dí kè tè shì jì |
| Biuret/ˈbɪjuːrət/ | 双缩脲 | shuāng suō niào |
| emulsion/ɪˈmʌlʃn/ | 乳浊液 | rǔ zhuó yè |
| control/kənˈtrəʊl/ | 对照 | duì zhào |
Testing for food molecules
- How do you prove a food contains starch, sugar, protein or fat? With simple food tests 食物检测 that change colour.
- Each test gives a clear, named colour change.
检验食物分子
- 你如何证明一种食物含有淀粉、糖、蛋白质或脂肪?用改变颜色的简单食物检验(food tests)。
- 每个检验给出一个清晰的、有名字的颜色变化。
Food test lab · 食物检测实验
Follow how the test result reveals the nutrient in a sample. · 了解测试结果如何揭示样本中的营养成分。
A positive iodine test for starch gives a: · 碘测试淀粉呈阳性时给出：
Iodine turns blue-black with starch. · 碘遇淀粉变蓝黑色。
Benedict's solution, when heated with a reducing sugar, turns: · 本尼迪特试剂与还原糖加热后变为：
Benedict's goes blue → brick-red with reducing sugar. · 本尼迪特试剂遇还原糖由蓝色变为砖红色。
Starch and sugar
- Starch: add iodine 碘 solution → turns from orange-brown to blue-black.
- Reducing sugar 还原糖: add Benedict's 本尼迪克特试剂 solution and heat → turns from blue to brick-red.
Each food test gives its own colour change for a positive result
淀粉和糖
- 淀粉:加碘(iodine)溶液 → 从橙棕色变成蓝黑色。
- 还原糖(reducing sugar):加本尼迪特(Benedict's)溶液并加热 → 从蓝色变成砖红色。
每个食物检验为一个阳性结果给出它自己的颜色变化
Match each food molecule to its test result. · 将每种食物分子与其测试结果匹配。
Each test gives a distinct colour change. · 每种测试都会产生明显的颜色变化。
The ______ test turns purple when protein is present. · ______测试在存在蛋白质时变为紫色。
Biuret detects protein (blue → purple). · 双缩脲试剂检测蛋白质（蓝色→紫色）。
Protein and fat
- Protein: add Biuret 双缩脲 solution → turns from blue to purple/violet.
- Fat: the ethanol (emulsion 乳浊液) test → a cloudy white emulsion forms.
Bread is rich in carbohydrates, one of the main food groups
蛋白质和脂肪
- 蛋白质:加双缩脲(Biuret)溶液 → 从蓝色变成紫色/紫罗兰色。
- 脂肪:乙醇(乳浊液)检验(ethanol/emulsion test)→ 形成一个乳白色乳浊液。
面包富含碳水化合物,主要食物组之一
The Benedict's test for reducing sugar must be heated. · 本尼迪特试剂检测还原糖时必须加热。
Benedict's needs heating in a water bath; the others are done cold. · 本尼迪特试剂需水浴加热；其余测试在冷态下进行。
Doing tests safely and fairly
- Benedict's test must be heated (in a water bath); the others are done cold.
- Use a control 对照 (a sample you know the result of) to check the test works.
Worked example. A student tests milk. Biuret turns purple (protein present) and the emulsion test goes cloudy (fat present) — so milk contains both protein and fat.
Carbohydrates and fats contain C, H and O; proteins also contain nitrogen
安全而公平地做检验
- 本尼迪特检验必须加热(在一个水浴中);其他的在冷的情况下做。
- 使用一个对照(control,一个你知道结果的样品)来检查检验有效。
例题。 一个学生检验牛奶。双缩脲变紫色(蛋白质存在),乳浊液检验变浑浊(脂肪存在)——所以牛奶含有蛋白质和脂肪两者。
You've got it
- iodine → blue-black = starch; Benedict's (heated) → brick-red = reducing sugar
- Biuret → purple = protein; ethanol/emulsion → cloudy white = fat
- only Benedict's needs heating; use a control to check the test
你掌握了
- 碘 → 蓝黑色 = 淀粉;本尼迪特(加热)→ 砖红色 = 还原糖
- 双缩脲 → 紫色 = 蛋白质;乙醇/乳浊液 → 乳白色 = 脂肪
- 只有本尼迪特需要加热;使用一个对照来检查检验